How can I make a box like product packet?
Set the Base material. I just used a Diffuse BSDF Orange.



Load up your image for the front of the packet. I used the a Color Grid generated in Blender.



Select required faces and Unwrap. I deliberately left a border so you can see the base material. This will create a default UV Map



Set up material Nodes to start with and Input->UV Map set to the default map connected to an Texture->Image with your image. Make sure it is set to Clip then take that through a Diffuse BSDF Shader and Mix it with the Base.



Now add a new UV Map and select the next faces and Unwrap



Now you can duplicate your existing Nodes and change the UV Map input and use a Mix Shader to combine them. I have used the same image but you can choose a different source image for the back.



Just to show how you can manipulate the unwrapped island. Scaled and rotated.



Commonly and especially for games, people will use a single image and unwrap to a part of it. I find multiple UVMaps gives me more control.